The present invention relates to a fuel supplying pump and more particularly to improved control means thereof.
A typical conventional fuel supplying pump has a structure and operation as described hereafter with reference to FIGS. 1 and 2. As shown in FIG. 1, the fuel supplying pump 2 is provided in a fuel tank 4 being supported by a supporting strip 6. The fuel supplying pump 2 sucks fuel in the fuel tank 4 through a suction port 8 and exhausts the sucked fuel through an output port 10.
FIG. 2A shows a cross sectional elevation view of the fuel supplying pump. A rotating shaft 52 is rotatively fixed in a casing 46. The casing 46 comprises a cylindrical body 54, an upper supporting member 20, a pump bracket 42 and a bottom cap 38. The rotating shaft 52 is rotatively supported by metal bearings 24. A detecting magnet 22 and an armature 50 are fixed to the rotating shaft 52. Surrounding the armature 50 with a small gap in between is a yoke 26 having three field windings 28 wound thereon. The yoke 26 is fixed to the inner side of the cylindrical body 54. Electrification of the field windings 28 are controlled by a control circuit 62 so as to generate three phase magnetic field.
At the lower end of the rotating shaft 52, a pump rotor 36 is provided. The pump rotor 36 is rotated in a pump chamber 40 and sucks the fuel through the suction port 8. The sucked fuel is conveyed through a hole 34 and a chamber 30 and is output from the output port 10. A relief valve 44 is provided for limiting a pressure in the chamber 30 within safety range.
On the top surface of the upper supporting member 20, a base plate 58 having a flange 72 is fixed.
The control circuit 62 which detects the rotation of detecting magnet 22 and controls current supplying of the windings 28, is provided on the base plate 58. The control circuit 62 is covered with cover 70. Lead wires 66 are provided passing through the cover 70 and are connected to the control circuit 62 for supplying the power.
FIG. 2B shows a top view of the control circuit 62. On the upper surface of the base plate 58, a board 78 having three Hall elements 76 and IC 68 are fixed. The collectors of power tansistors 60, 60, 60 are connected to corresponding windings 28 by leads 74, respectively.
The operation of the typical conventional fuel supplying pump is described hereafter. The Hall elements 76 generate magnetic field signals corresponding to the rotation of the detecting magnet 22. The magnetic field signals are processed by the IC 68 and control the power transistors 60. The power transistors 60 switch the current of the windings 28, and thus generate a three phase magnetic field. By the three phase magnetic field, the armature 50 and the rotating shaft 52 are rotated. Therefore, the rotor 36 connected to the rotating shaft 52 is rotated, and thus transfers the fuel from the suction port 8 to the output port 10.
A switching circuit 82 receives a signal from an engine (not shown) through a lead wire 200. The switching circuit 82 is covered by a case and is provided in an instrument panel of a car. The switching circuit 82 receives a signal from a conventional switch when that switch detects that the engine has stopped or that the engine speed has decreased a predetermined value. Such a reduction in engine speed may be cuased by a break in the fuel pipe. The switching circuit 82 responds by stopping the fuel supplying pump so as to prevent fuel from further flowing out.
In such a conventional fuel supplying pump, since the switching circuit 82 is provided separate from the fuel supplying pump and provided in the instrument panel, the wire connection work is complex and a particular space therefore is necessary for providing the switching circuit in the instrument panel.